In Vitro Accuracy of Two Different Electronic Apex Locators Under Various Conditions

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors are commended for the thought process and efforts put into developing the current manuscript.

While the study may be of good interest to the readers there are questions and concerns that needs clarification to improve the quality of the manuscript.

The introduction is quite short, not cohesive and lacks adequate literature support. Also, the scientific justification for the current study is insufficient.

Material and methods - This section is not clear.
How was the sample size determined?
What were the experimental groups and how was the sample of 40 teeth distributed?
Is there a control group?
What was the rationale for selecting the two EAL in the study?
Why were the EALs not compared with a gold standard EAL?
Why was the red line the reference point on Raypex and not the last green position? does this not signify beyond the apex? A representative images of experimental set up should be included for clarification.
Why was the reading conducted with the canal full with each irrigating solution? This is not ideal in clinical practice, there are enough scientific evidences that proved the presence of any irrigating solution within the root canal interferes with the accuracy of apex locator readings. 

Tables - The tables are not clear to read and understand. The variables could have been tabulated in a more clear way.

Discussion -  This section is similar to the introduction, the paragraphs are not cohesive and the findings are not well debated with the clinical relevance of the study. Also there is no clear narration on the strength and limitations of the study.

Author Response

Dear Reviewer,

thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted in yellow/in re-submitted files.

 

Reviewer 1

 

1. The introduction is quite short, not cohesive and lacks adequate literature support. Also, the scientific justification for the current study is insufficient.

We have added new references to the introduction and additional clarifications of the paper and its scientific contribution. We have added null hypothesis to clarify the aim. We have rearranged introduction to be more understandable.

 

2. Material and methods - This section is not clear.

               We have rearranged this section, according to reviewers commnets.

3. How was the sample size determined?

 

According to the papers published before which we cite in Materials, and other searched published papers with this topic, they usually used 20-40 teeth for analysis in vitro. So, we quote some published papers, and most of them are used as references in our paper:

 

N= 45 samples.  Ebrahim AK, Wadachi R, Suda H. An in vitro evaluation of the accuracy of Dentaport ZX apex locator in enlarged root canals. Aust Dent J 2007;52(3):193-197.

 

N=10 samples. Kaufman AY, Keila S, Yoshpe M. Accuracy of a new apex locator: an in vitro study. Int Endod J. 2002;35(2):186-92. 

 

N=40 samples. Kang JA, Kim SK. Accuracies of seven different apex locators under various conditions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;106(4):e57-62.

 

N=40 samples. Bernardes RA, Duarte MA, Vasconcelos BC, Moraes IG, Bernardineli N, Garcia RB, Baldi JV, Victorino FR, Bramante CM. Evaluation of precision of length determination with 3 electronic apex locators: Root ZX, Elements Diagnostic Unit and Apex Locator, and RomiAPEX D-30. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007;104(4):e91-4. 

N=40 samples. Guise GM, Goodell GG, Imamura GM. In vitro comparison of three electronic apex locators. J Endod. 2010;36(2):279-81. 

N=30 samples. Bilaiya S, Patni PM, Jain P, Pandey SH, Raghuwanshi S, Bagulkar B. Comparative Evaluation of Accuracy of Ipex, Root Zx Mini, and Epex Pro Apex Locators in Teeth with Artificially Created Root Perforations in Presence of Various Intracanal Irrigants. Eur Endod J. 2020;5(1):6-9. 

 

We have inserted explanation in Materials section. Also, the sample size can be determined using Statistical power analysis software with alpha-type error of 0.05, and power of statistics 0.8. The output indicated a minimal sample size of 34 teeth. We can also insert power analysis, although we have not found it used in previous published papers, except work from Bilaiya S. (2020).

 

 

4. What were the experimental groups and how was the sample of 40 teeth distributed?

According to this work and the methodology that has been published and explained in previous studies, no control group is used. All groups are conditionally "experimental" because they measure different irrigation agents and compare it to the gold standard - Actual Canal Length (ACL). Every canal irrigation agent was used in sample of 40 teeth(roots) and the canals were thoroughly rinsed with distilled water and dried with paper points before applying another irrigant solution.

 

 

5. Is there a control group?

As with similar studies of this type, we did not have a control group. All canal irrigation materials show a more or less impact on the accuracy of EALs measurement. Therefore, we have the gold standard as other studies, which is ACL measured by microscope. In theory, the control group could be 0.9% saline solution, but this canal irrigant also affects the EAL measurement due to its electroconductivity. We did not find any other studies on this topic that used a control group.

 

6. What was the rationale for selecting the two EAL in the study?

We used two different endometers to analyze their accuracy, being a 5th generation EAL (Raypex) and a 4th generation EAL (Ipex). Recently published paper, which we used as reference, describes several different generations of EAL. (Nasiri K, Wrbas KT. Accuracy of different generations of apex locators in determining working length; a systematic review and meta-analysis. Saudi Dent J. 2022;34(1):11-20. )

We have inserted this statement  into manuscript.

 

7. Why were the EALs not compared with a gold standard EAL?

Our Gold standard was ACL-direct and correct measurement of actual canal length under microscope.  For example, Carvalho (Braz Oral Res. 2010;24(4):394-8) uses Gold Standard (GS): “Aided by the use of an operative microscope under 10 magnification, a size 10 K file was inserted into each canal until the tip became visible at the major apical foramen and a rubber stop was then positioned at the coronal reference point.”

So, all measurements with various canal irrigants (EAL) were compared to the ACL to determine accuracy. We have inserted additional explanation in Materials part.

8. Why was the red line the reference point on Raypex and not the last green position? does this not signify beyond the apex? A representative images of experimental set up should be included for clarification.

 

According to Raypex manufacturer and instructions, the last red line represents  apical foramen:

“1 rötliches Segment: Erreichen des Foramen apicale/“1 reddish segment: reaching the apical foramen”.

So, red dot after last red line is beyond the apical foramen, and we did not use this position. We have inserted  picture of EAL and design model.

9. Why was the reading conducted with the canal full with each irrigating solution? This is not ideal in clinical practice, there are enough scientific evidences that proved the presence of any irrigating solution within the root canal interferes with the accuracy of apex locator readings. 

According to almost all studies on this topic, excess irrigation fluid was removed from the cavity with cotton swabs or pellets, but the rest of the fluid remained in the canals in order to analyze its influence on the accuracy of different apex locators. Therefore, we conducted this study to analyze the impact of different irrigants on the accuracy of apex locators. The results of this study may help in clinical work by providing a better understanding of which irrigants should be avoided due to their excessive impact on the accuracy of apex locators. We quote some published papers.

“The canals were irrigated with 2.5% NaOCl. Cotton pellets were used to dry the tooth surface and to eliminate the excess irrigating solution.” Gurel MA, Helvacioglu Kivanc B, Ekici A. A comparative assessment of the accuracies of Raypex 5, Raypex 6, iPex and iPex II electronic apex locators: An in vitro study. J Istanb Univ Fac Dent. 2017 ;51(1):28-33.

“During the experiment, the root canals were irrigated with the irrigation solution of interest using an endodontic syringe; the pulp chamber was dried with cotton pellets leaving the canal filled with the irrigating solution. Alhadlaq, Solaiman. (2012). Evaluation of Two Compact Electronic Apex Locators in The Presence of Different Endodontic Solutions. Hydrometallurgy. 3. 10.1016/j.ksujds.2011.10.003.

“Each canal was filled with 2 mL of irrigant, and the excess fluid was drained with a cotton pellet. Marek E, Łagocka R, Kot K, Woźniak K, Lipski M. The influence of two forms of chlorhexidine on the accuracy of contemporary electronic apex locators. BMC Oral Health. 2019 Dec 31;20(1):3.

“After root canal preparation, EL measurements were taken with various irrigants in the root canals…. Kaufman AY, Keila S, Yoshpe M. Accuracy of new apex locator: an in vitro study. Int Endod J. 2002;35:186–192.

 

It is also known that this is a standard procedure in endodontics, chemical-mechanical cleaning of the canals with an irrigant, which, in addition to its disinfecting and dissolving properties, also has the property of lubricating and preventing breakage of endodontic instruments. Therefore, in clinical practice, it is desirable to keep the canal moist with an irrigant when performing cleaning and shaping of canal.

 

 

10. Tables - The tables are not clear to read and understand. The variables could have been tabulated in a more clear way.

We have improved tables and inserted explanations to be more understandable to readers.

 

11. 
    
    Discussion -  This section is similar to the introduction, the paragraphs are not cohesive and the findings are not well debated with the clinical relevance of the study. Also there is no clear narration on the strength and limitations of the study.

We have inserted new references and more data relevant for this study. We have inserted limitations of this study. Also, according to other Reviewers, we have inserted more data and explanations into Discussion section.

Reviewer 2 Report

Comments and Suggestions for Authors

R51-R54 - should be shortly described how, since is the central subject.

R59 - negotiate? incomprehensible in this context.

R58-R61 - the phrases are broken, and seem thrown in text. They should be emphasyzed and connected in order to finalize with the purpose.

R66 - the authors must choose one protocole only.

table 2 - revised for spacing

R244 - the authors must insist on their personal insights regarding the irrigants influence over measurements accuracy (reasons, possible mechanism, future perspectives).

 

Author Response

Dear Reviewer,

thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted in yellow/in re-submitted files.

 

 

Comments and Suggestions for Authors

 

R51-R54 - should be shortly described how, since is the central subject.

According to the Reviewer 1 and 3, we have described it in Discussing part as well adding new references. Also, we have inseted more explanations in Introduction part.

 

 

R59 - negotiate? incomprehensible in this context.

Corrected.

 

R58-R61 - the phrases are broken, and seem thrown in text. They should be emphasyzed and connected in order to finalize with the purpose.

Corrected.

R66 - the authors must choose one protocole only.

According to the Reviewer 1, we have choose three references for protocol which are fundamental for this type of paper. I hope this will be no problem and we can agree.

table 2 - revised for spacing

Corrected.

 

R244 - the authors must insist on their personal insights regarding the irrigants influence over measurements accuracy (reasons, possible mechanism, future perspectives).

Corrected. According to Revier No.1, we have inserted more data into Discussion part.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

Your paper is really interesting, but there are some flaws and need some improvement.

1. Abstract:
   1. Remove the subheadings following the template's instructions.
   2. A sentence would be missing to introduce the objective in the Background section.
   3. Follow the template's instructions for the keywords.
2. On line 39 fix the error in the reference.
3. It is a subject that has been well studied in the literature, but the reason or relevance of this research needs to be further justified, as the paragraph where it is done just before the introduction is rather weak. You should highlight the novelty of the research if it exists.
4. The first two paragraphs on results, lines from 122 to 131, there will be moved to Materials & Methods in a subsection with the heading of Statistical analysis.
5. You should fix the bibliographical references on lines 189 and 190 of the discussion.
6. In the discussion you talk all the time about sodium hypochlorite, your hypochlorite group is Chlorcid 3%, you should remember that before you start comparing the results with the other studies.
7. In relation to hypochlorite, can the variability of hypochlorite concentrations in the different studies affect the results obtained and make comparison difficult? Because perhaps this should be explained a little more in the discussion. The same in relation to EDTA, since in your study you use different concentrations and compare them with the rest of the literature, which does not always coincide either, please comment on this variability and explain the most.
8. Remove the Acknowledgements section as it has not been filled in.
9. Did you pass some kind of ethics committee? I say this because they use natural teeth, they say in the manuscript that the extractions were done for therapeutic reasons of different kinds, but then they don't even refer to the ethics committee, and they say that it doesn't apply to informed consent, when in theory it is relevant and needed to do the extractions.
10. You should revise the template to include the list of references as requested by the journal.
11. Yoy have only listed 5 references from the last 5 years, two of which are reviews and meta-analyses, which shows that this is a well-studied topic and does not represent any novelty.

Author Response

Dear Reviewer,

thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted in yellow/in re-submitted files.

 

Rev. 3

 

1. Abstract:

 

1. Remove the subheadings following the template's instructions.

Corrected.

1. A sentence would be missing to introduce the objective in the Background section.

Corrected.

1. Follow the template's instructions for the keywords.

Corrected.

1. On line 39 fix the error in the reference.

Corrected.

1. It is a subject that has been well studied in the literature, but the reason or relevance of this research needs to be further justified, as the paragraph where it is done just before the introduction is rather weak. You should highlight the novelty of the research if it exists.

According to Reviewer No.1 also , we have inserted more data about aim of the work, hypothesis and clinical relevance.

1. The first two paragraphs on results, lines from 122 to 131, there will be moved to Materials & Methods in a subsection with the heading of Statistical analysis.
   Corrected.
2. You should fix the bibliographical references on lines 189 and 190 of the discussion.

Corrected

1. In the discussion you talk all the time about sodium hypochlorite, your hypochlorite group is Chlorcid 3%, you should remember that before you start comparing the results with the other studies.

We have corrected and insert more explanations about Chlorcid and its composition (3% NaOCl). Also, more data are now in Discussion part about differences of  NaOCl concentrations solutions and its influence on EALs.

1. In relation to hypochlorite, can the variability of hypochlorite concentrations in the different studies affect the results obtained and make comparison difficult? Because perhaps this should be explained a little more in the discussion. The same in relation to EDTA, since in your study you use different concentrations and compare them with the rest of the literature, which does not always coincide either, please comment on this variability and explain the most.

In accordance with the other Reviewers, we have explained this problem in more detail with new references in the Discussions section.

 

1. Remove the Acknowledgements section as it has not been filled in.
            Corrected.
2. Did you pass some kind of ethics committee? I say this because they use natural teeth, they say in the manuscript that the extractions were done for therapeutic reasons of different kinds, but then they don't even refer to the ethics committee, and they say that it doesn't apply to informed consent, when in theory it is relevant and needed to do the extractions.
            Corrected. The research passed the faculty ethics committee. Furthermore, the extracted teeth that were used in this in vitro work were collected from patients during regular indicated procedures (mostly surgery). Patients fill out the informed consent and protocol during treatment that the data and materials can be used for scientific purposes.
3. You should revise the template to include the list of references as requested by the journal.

Corrected.

1. Yoy have only listed 5 references from the last 5 years, two of which are reviews and meta-analyses, which shows that this is a well-studied topic and does not represent any novelty.

In line with other reviewers, we found additional references that we included in this paper and covered almost all in vitro papers on this topic over the past 15 years or more. We must be careful because many papers differ in methodology (ex vivo, in vivo, perforated canals, retreatment, flaring and preflaring etc) and research objectives. Therefore, our research used two different EALs (4th and 5th generation) and the 7 most common root canal irrigation materials, so that the results would have an impact on clinical work. We can conclude that this topic is still being systematically studied because new combinations of root canal irrigation materials and different EALs are constantly coming onto the market, making it difficult for the clinician to choose the right protocol and best EAL device. Nasiri et al (2021) suggest: ”…that more in vivo or in vitro studies, in which all generations of devices are examined and compared, be performed to obtain more precise and valid data on the accuracy of different generations of EALs.”

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

Thank you for the revision. However, the explanation on how the sample size was calculated and also the overall experimental has not addressed the concerns raised.

Author Response

Thanks for the review. We entered data on the sample size and its statistical analysis in the chapter Statistical analysis.

Furthermore, we used an experimental model for this in vivo research that is well documented and verified in previous researches, and we provide references to some of them in the paper (first version of Manuscript, references No.7, 17-20, 22, 24- 30. Latest version of manuscript/only crucial: references 7,18-20) If additional clarification of the experimental model is needed, we can do it.

Reviewer 2 Report

Comments and Suggestions for Authors

Regarding your Cover letter:

Latin words - must be written in italics.

R66 - needs reference and examples.

R83 - around 40 samples is scientificc misleading.

 

Author Response

Latin words - must be written in italics.

Thank you for your comments. All Latin words has been changed to italics.

R66 - needs reference and examples.

we have reformulated the claim according to possible impact. In the discussion, we cite references 45,46 on the influence of different electroconductive media on EALs.

R83 - around 40 samples is scientificc misleading.

Corrected,.

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for do all the changes.

Author Response

Dear Reviewer, 

thank you for your help in improving our manuscript.